Where: As = peak asymmetry factor b = distance from the point at peak midpoint to the trailing edge (measured at 10% of peak height) a = distance from the leading edge of of peak to the midpoint (measured at 10% of peak height)

Calculation of Tailing Factor (USP method)

Where: T = tailing factor (measured at 5% of peak height) b = distance from the point at peak midpoint to the trailing edge a = distance from the leading edge of the peak to the midpoint

Dimensions: when using HPLC or UHPLC columns, H is usually expressed in µm.

Calculation of Reduced Plate Height (h)

Giddings introduced dimensionless parameters for H and also for the linear velocity. Dimensionless parameters allow the direct comparison of the efficiency of two or more columns packed with different particle size packing materials. According to the theory, a well packed column should have a reduced plate height (h) in the range of 2-3 at a reduced velocity (v) of about 3. Here we only provide the formula for h.